The present invention relates to a process for reducing the mean particle size of resilient porous organic polymer particles having open cell pores which resist particle size reduction due to the compressibility and resiliency of the organic polymer. Further, the present invention relates to novel products produced by the process for reducing the mean particle size and to particles of reduced mean particle size which have a functional release additive contained in the pores thereof.
The present invention further relates to an improved lead acid battery element containing metal impurity inhibiting porous polymeric additives which are added to the positive active material, negative active material and/or battery separator to inhibit the detrimental effects of certain metals on the efficiency of a lead acid battery, particularly the negative plate battery element and to polymeric macroporous additives that enhance active material utilization efficiency and improvement in the utilization of sulfuric acid electrolyte necessary for the discharge reaction of a lead acid battery which are produced by the process of this invention.
Resilient porous organic polymers resist permanent deformation and have been found to be difficult to process, if at all, for size reduction in conventional grinding processes. Conventional grinding processes are typically used to grind and produce particle size reduction for solid type particles which have little or no compressibility and which can vary in particle hardness. Typical grinding processes such as universal mills, slurry mills, fluid energy mills, cone mills and hammer mills are generally effective for such solid type particles, particularly brittle type particles. One of the problems with the use of conventional grinding mills for size reduction of resilient porous organic polymers is that the particles compress under the applied forces, i.e., the particles are compressible and regain substantially the same geometry when the force is removed. Unlike solid particles particularly, brittle particles, the conventual grinding mill approaches used for dry solid particles produces substantially less or even no size reduction of resilient porous polymers in the dry powder form. Further, attrition type grinding mills have had little overall effectiveness when the organic polymers were incorporated into a liquid slurry.
In many applications that use porous organic polymers as additives such as the use of additives in lead acid batteries, it is preferred to have a non-spherical geometry such as an elongated geometry and/or a geometry that has a length to diameter which is greater than one, in order to provide improved overall performance of the additive. It is therefore desirable to produce porous organic particles of reduced size by processes which produce a non-spherical geometry.
Thus, for the many applications in which porous organic polymers are used, particularly there use as additives, wherein a reduced particle size and/or particle size distribution offers performance advantages, there is a need for a process which is effective for reducing the particle size of resilient porous organic particles at reasonable process conditions and processing times, particularly processing conditions at atmospheric pressure and ambient temperatures at preferably commercial scale processing times.